scholarly journals Quantitative mismatch between empirical temperature-size rule slopes and predictions based on oxygen limitation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sigurd Einum ◽  
Claus Bech ◽  
Øystein Nordeide Kielland
Keyword(s):  
Body Size ◽  
Phenotypic Plasticity ◽  
Supply And Demand ◽  
Oxygen Limitation ◽  
Size Distributions ◽  
Deterministic Models ◽  
Future Studies ◽  
Temperature Regimes ◽  
Order Of Magnitude

AbstractIn ectotherms, adult body size commonly declines with increasing environmental temperature, a pattern known as the temperature-size rule. One influential hypothesis explaining this observation is that the challenge of obtaining sufficient oxygen to support metabolism becomes greater with increasing body size, and more so at high temperatures. Yet, previous models based on this hypothesis do not account for phenotypic plasticity in the physiology of organisms that counteracts oxygen limitation at high temperature. Here, we model the predicted strength of the temperature-size response using estimates of how both the oxygen supply and demand is affected by temperature when allowing for phenotypic plasticity in the aquatic ectotherm Daphnia magna. Our predictions remain highly inconsistent with empirical temperature-size responses, with the prior being close to one order of magnitude stronger than the latter. These results fail to provide quantitative support for the hypothesis that oxygen limitation drives temperature-size clines in aquatic ectotherms. Future studies into the role of oxygen limitation should address how the strength of the temperature-size response may be shaped by evolution under fluctuating temperature regimes. Finally, our results caution against applying deterministic models based on the oxygen limitation hypothesis when predicting future changes in ectotherm size distributions under climate change.

scholarly journals Quantitative Mismatch Between Empirical Temperature-Size Rule Slopes and Predictions Based on Oxygen Limitation

2021 ◽  
Author(s):  
Sigurd Einum ◽  
Claus Bech ◽  
Øystein Nordeide Kielland
Keyword(s):  
Body Size ◽  
Phenotypic Plasticity ◽  
Supply And Demand ◽  
Oxygen Limitation ◽  
Size Distributions ◽  
Deterministic Models ◽  
Future Studies ◽  
Temperature Regimes ◽  
Order Of Magnitude

Abstract In ectotherms, adult body size commonly declines with increasing environmental temperature, a pattern known as the temperature-size rule. One influential hypothesis explaining this observation is that the challenge of obtaining sufficient oxygen to support metabolism becomes greater with increasing body size, and more so at high temperatures. Yet, previous models based on this hypothesis do not account for phenotypic plasticity in the physiology of organisms that counteracts oxygen limitation at high temperature. Here, we model the predicted strength of the temperature-size response using estimates of how both the oxygen supply and demand is affected by temperature when allowing for phenotypic plasticity in the aquatic ectotherm Daphnia magna. Our predictions remain highly inconsistent with empirical temperature-size responses, with the prior being close to one order of magnitude stronger than the latter. These results fail to provide quantitative support for the hypothesis that oxygen limitation drives temperature-size clines in aquatic ectotherms. Future studies into the role of oxygen limitation should address how the strength of the temperature-size response may be shaped by evolution under fluctuating temperature regimes. Finally, our results caution against applying deterministic models based on the oxygen limitation hypothesis when predicting future changes in ectotherm size distributions under climate change.

THE ROLE OF CLIMATE IN SHAPING MAMMALIAN BODY SIZE DISTRIBUTIONS OVER THE CENOZOIC

2016 ◽  
Author(s):  
S. Kathleen Lyons ◽  
◽  
Felisa A. Smith ◽  
S.K. Morgan Ernest
Keyword(s):  
Body Size ◽  
Size Distributions

scholarly journals Patterns in estuarine macrofauna body size distributions: The role of habitat and disturbance impact

2014 ◽  
Vol 85 ◽  
pp. 404-412 ◽  
Author(s):  
Marina Dolbeth ◽  
Dave Raffaelli ◽  
Miguel Ângelo Pardal
Keyword(s):  
Body Size ◽  
Size Distributions

Mesophyll conductance: the leaf corridors for photosynthesis

2020 ◽  
Vol 48 (2) ◽  
pp. 429-439 ◽  
Author(s):  
Jorge Gago ◽  
Danilo M. Daloso ◽  
Marc Carriquí ◽  
Miquel Nadal ◽  
Melanie Morales ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Current Knowledge ◽  
Main Role ◽  
Mesophyll Conductance ◽  
Future Studies ◽  
Cell Structures ◽  
Leaf Tissues ◽  
Change Framework ◽  
Chloroplast Stroma

Besides stomata, the photosynthetic CO2 pathway also involves the transport of CO2 from the sub-stomatal air spaces inside to the carboxylation sites in the chloroplast stroma, where Rubisco is located. This pathway is far to be a simple and direct way, formed by series of consecutive barriers that the CO2 should cross to be finally assimilated in photosynthesis, known as the mesophyll conductance (gm). Therefore, the gm reflects the pathway through different air, water and biophysical barriers within the leaf tissues and cell structures. Currently, it is known that gm can impose the same level of limitation (or even higher depending of the conditions) to photosynthesis than the wider known stomata or biochemistry. In this mini-review, we are focused on each of the gm determinants to summarize the current knowledge on the mechanisms driving gm from anatomical to metabolic and biochemical perspectives. Special attention deserve the latest studies demonstrating the importance of the molecular mechanisms driving anatomical traits as cell wall and the chloroplast surface exposed to the mesophyll airspaces (Sc/S) that significantly constrain gm. However, even considering these recent discoveries, still is poorly understood the mechanisms about signaling pathways linking the environment a/biotic stressors with gm responses. Thus, considering the main role of gm as a major driver of the CO2 availability at the carboxylation sites, future studies into these aspects will help us to understand photosynthesis responses in a global change framework.

Motives for Social Isolation Following a Negative Emotional Episode

2018 ◽  
Vol 77 (3) ◽  
pp. 127-131
Author(s):  
Gérald Delelis ◽  
Véronique Christophe
Keyword(s):  
Social Isolation ◽  
Social Affiliation ◽  
Semantic Categorization ◽  
Future Studies ◽  
Cognitive Regulation ◽  
Emotional Event ◽  
Regulation Strategies ◽  
Emotional Events

Abstract. After experiencing an emotional event, people either seek out others’ presence (social affiliation) or avoid others’ presence (social isolation). The determinants and effects of social affiliation are now well-known, but social psychologists have not yet thoroughly studied social isolation. This study aims to ascertain which motives and corresponding regulation strategies participants report for social isolation following negative emotional events. A group of 96 participants retrieved from memory an actual negative event that led them to temporarily socially isolate themselves and freely listed up to 10 motives for social isolation. Through semantic categorization of the 423 motives reported by the participants, we found that “cognitive clarification” and “keeping one’s distance” – that is, the need for cognitive regulation and the refusal of socioaffective regulation, respectively – were the most commonly and quickly reported motives for social isolation. We discuss the findings in terms of ideas for future studies aimed at clarifying the role of social isolation in health situations.

Ecology and biogeography in the introduction to “De bestiis marinis” by Georg Wilhelm Steller

2019 ◽  
Vol 46 (1) ◽  
pp. 63-74
Author(s):  
Stefano Mattioli
Keyword(s):  
Body Size ◽  
Phenotypic Plasticity ◽  
Geographical Distribution ◽  
Functional Traits ◽  
Marine Mammals ◽  
Main Part ◽  
Wide Distribution ◽  
Restricted Range ◽  
Direct Influence ◽  
Modern Biology

The rediscovery of the original, unedited Latin manuscript of Georg Wilhelm Steller's “De bestiis marinis” (“On marine mammals”), first published in 1751, calls for a new translation into English. The main part of the treatise contains detailed descriptions of four marine mammals, but the introduction is devoted to more general issues, including innovative speculation on morphology, ecology and biogeography, anticipating arguments and concepts of modern biology. Steller noted early that climate and food have a direct influence on body size, pelage and functional traits of mammals, potentially affecting reversible changes (phenotypic plasticity). Feeding and other behavioural habits have an impact on the geographical distribution of mammals. Species with a broad diet tend to have a wide distribution, whereas animals with a narrow diet more likely have only a restricted range. According to Steller, both sea and land then still concealed countless animals unknown to science.

The role of hormones

2018 ◽  
Author(s):  
H. Frederik Nijhout ◽  
Emily Laub
Keyword(s):  
Phenotypic Plasticity ◽  
Social Behavior ◽  
Parental Care ◽  
Juvenile Hormone ◽  
Reproductive Behavior ◽  
Hormonal Control ◽  
Plastic Trait

Many behaviors of insects are stimulated, modified, or modulated by hormones. The principal hormones involved are the same as the ones that control moulting, metamorphosis, and other aspects of development, principally ecdysone and juvenile hormone. In addition, a small handful of neurosecretory hormones are involved in the control of specific behaviors. Because behavior is a plastic trait, this chapter begins by outlining the biology and hormonal control of phenotypic plasticity in insects, and how the hormonal control of behavior fits in with other aspects of the control of phenotypic plasticity. The rest of the chapter is organized around the diversity of behaviors that are known to be controlled by or affected by hormones. These include eclosion and moulting behavior, the synthesis and release of pheromones, migration, parental care, dominance, reproductive behavior, and social behavior.

scholarly journals A 3D study on the amplification of regional haze and particle growth by local emissions

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Wei Du ◽  
Lubna Dada ◽  
Jian Zhao ◽  
Xueshun Chen ◽  
Kaspar R. Daellenbach ◽  
...  
Keyword(s):  
Atmospheric Stability ◽  
Ground Level ◽  
Particle Growth ◽  
Chemical Compositions ◽  
Size Distributions ◽  
Aerosol Composition ◽  
Regional Haze ◽  
Haze Formation ◽  
Beijing China

AbstractThe role of new particle formation (NPF) events and their contribution to haze formation through subsequent growth in polluted megacities is still controversial. To improve the understanding of the sources, meteorological conditions, and chemistry behind air pollution, we performed simultaneous measurements of aerosol composition and particle number size distributions at ground level and at 260 m in central Beijing, China, during a total of 4 months in 2015–2017. Our measurements show a pronounced decoupling of gas-to-particle conversion between the two heights, leading to different haze processes in terms of particle size distributions and chemical compositions. The development of haze was initiated by the growth of freshly formed particles at both heights, whereas the more severe haze at ground level was connected directly to local primary particles and gaseous precursors leading to higher particle growth rates. The particle growth creates a feedback loop, in which a further development of haze increases the atmospheric stability, which in turn strengthens the persisting apparent decoupling between the two heights and increases the severity of haze at ground level. Moreover, we complemented our field observations with model analyses, which suggest that the growth of NPF-originated particles accounted up to ∼60% of the accumulation mode particles in the Beijing–Tianjin–Hebei area during haze conditions. The results suggest that a reduction in anthropogenic gaseous precursors, suppressing particle growth, is a critical step for alleviating haze although the number concentration of freshly formed particles (3–40 nm) via NPF does not reduce after emission controls.

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